YOU SAID:

Rocks are being flung at them

INTO JAPANESE

岩は彼らに投げられている

BACK INTO ENGLISH

The rock is thrown by them

INTO JAPANESE

岩は彼らによって投げられる

BACK INTO ENGLISH

The rocks are thrown by them

INTO JAPANESE

岩は彼らによって投げられます

BACK INTO ENGLISH

The rocks are thrown by them